GPS receiver and method for processing GPS signals

• US 6,104,340 A
• Filed: 08/24/1998
• Issued: 08/15/2000
• Est. Priority Date: 10/09/1995
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Inventors: Krasner, Norman F.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US09/138,946
• Time in Patent Office: 722 Days
• Field of Search: 342/357, 701/213, 701/214
• US Class Current: 342/357.64
• CPC Class Codes: G01S 19/07 providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0054 of actual mobile position, i.e. position calculation on base station
• CPC Class Codes: G06F 2221/2111 Location-sensitive, e.g. geographical location, GPS
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H03D 7/163 the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H03J 2200/11 Cellular receiver, e.g. GSM, combined with a GPS receiver
• CPC Class Codes: H03J 7/06 using counters or frequency dividers
• CPC Class Codes: H04B 1/3805 : with built-in auxiliary receivers

Abstract

A global positioning system (GPS) receiver has first circuitry for receiving and processing pseudorandom sequences transmitted by a number of GPS satellites. The first circuitry is configured to perform conventional correlation operations on the received pseudorandom sequences to determine pseudoranges from the GPS receiver to the GPS satellites. The GPS receiver also includes second circuitry coupled to the first circuitry. The second circuitry is configured to receive and process the pseudorandom sequences during blockage conditions. The second circuitry processes the pseudorandom sequences by digitizing and stoning a predetermined record length of the received sequences and then performing fast convolution operations on the stored data to determine the pseudoranges. The GPS receiver may have a common circuitry for receiving GPS signals from in view satellites and downconverting the RF frequency of the received GPS signals to an intermediate frequency (IF). The IF signals are split into two signal paths; a first of which provides the conventional con-elation processing to calculate the pseudoranges. During blockage conditions, the IF signal is passed to the second signal path wherein the IF signals are digitized and stored in memory and later processed using the fast convolution operations to provide the pseudoranges. Alternative arrangements for the two signal paths include separate downconverters or shared digitizers. One embodiment provides both signal paths on a single integrated circuit with shared circuitry executing computer readable instructions to perform GPS signal processing appropriate to the reception conditions.

Claims

1. A method for using a GPS receiver having a communication system, said method comprising:

activating said GPS receiver in a first mode of operation which comprises;

receiving first GPS signals from in view satellites;

demodulating said first GPS signals to extract satellite information regarding in view satellites and computing pseudorange information for said in view satellites;

activating said GPS receiver in a second mode of operation which comprises;

receiving second GPS signals from in view satellites;

receiving non-differential GPS satellite assistance data from said communication system, wherein said non-differential GPS satellite assistance data comprises Doppler information for in view satellites;

processing said second GPS signals to determine pseudoranges to in view satellites.

2. A method as in claim 1 wherein said satellite information in said first mode comprises first satellite ephemeris information for in view satellites, said first satellite ephemeris information being obtained from said first GPS signals.

3. A method as in claim 2 wherein said GPS receiver in said first mode determines a position of said GPS receiver from said pseudorange information and from said first satellite ephemeris information, and wherein said GPS receiver operates in said first mode without any assistance data from said communication system.

4. A method as in claim 1 wherein said GPS receiver is a dual mode GPS receiver.

5. A method as in claim 1 wherein said GPS receiver in said first mode determines a position of said GPS receiver from said pseudorange information and from said satellite information, and wherein in said second mode, said GPS receiver in said second mode determines said pseudoranges and transmits said pseudoranges for determination of said position of said GPS receiver.

6. A method as in claim 1 wherein during said first mode of operation, said satellite information is extracted from said first GPS signals and stored in a memory and wherein during said second mode of operation said satellite information is used to calculate a position of said GPS receiver.

7. A dual mode receiver comprising:

a communication system for receiving non-differential GPS satellite assistance data;

a GPS receiver coupled to said communication system, said GPS receiver having a first mode of operation and a second mode of operation, in said first mode said GPS receiver receives first GPS signals from in view satellites and demodulates said first GPS signals to extract satellite information regarding in view satellites and computes pseudorange information for said in view satellites, and in said second mode said GPS receiver receives second GPS signals from in view satellites and receives said non-differential GPS satellite assistance data from said communication system and processes said second GPS signals to determine pseudorange to in view satellites, wherein said non-differential GPS satellite assistance data comprises Doppler information for in view satellites.

8. A dual mode receiver as in claim 7 wherein said satellite information in said first mode comprises first satellite ephemeris information for in view satellites, said first satellite ephemeris information being obtained from said first GPS signals.

9. A dual mode receiver as in claim 8 wherein said GPS receiver in said first mode determines a position of said GPS receiver from said pseudorange information and from said first satellite ephemeris information, and wherein said GPS receiver operates in said first mode without any assistance data from said communication system.

10. A dual mode receiver as in claim 7 wherein said GPS receiver is a dual mode GPS receiver.

11. A dual mode receiver as in claim 7 wherein said GPS receiver in said first mode determines a position of said GPS receiver from said pseudorange information and from satellite information, and wherein in said second mode, said GPS receiver in said second mode determines said pseudoranges and transmits said pseudoranges for determination of said position of said GPS receiver.

12. A dual mode receiver as in claim 7 wherein during said first mode of operation, said satellite information is extracted from said first GPS signals and stored in a memory and wherein during said second mode of operation said satellite information is used to calculate a position of said GPS receiver.